| Abstract Scope |
Ni-based superalloys are known for their high strength and corrosion resistance at temperatures above 0.7 of their melting point, making them essential materials in the aerospace industry. This study aimed to evaluate the effect of solution heat treatment on the precipitates' stability in directionally solidified MAR-M247 castings. The investigation focused on the analysis of microstructure, chemical composition, phase constitution, phase transformation temperatures, and microhardness of fabricated castings. Techniques such as X-ray diffraction, scanning and transmission electron microscopy, energy-dispersive X-ray spectroscopy, thermodynamic simulation, and differential scanning calorimetry were employed. Solution heat treatment resulted in the dissolution of γ' precipitates, as well as the complete dissolution of (Cr, W, Mo)5B3 borides and Ni7(Hf, Zr)2 phases. Secondary γ' precipitates in dendritic regions displayed a finer, cube-like morphology compared to the as-cast state, while in the interdendritic regions, the secondary γ' precipitates exhibited a more complex morphology, originating from the coagulation of finer precipitates.
The authors gratefully acknowledge the funding by National Centre for Research and Development, Poland, under grant POIR.01.01.01-00-1335/20. |